Recovery of sulphur from roaster gases



Jan. 19, 1932. R. F. BACON ,842,230 a RECOVERY OF SULPHUR FROM ROASTERGASES Filed May 9. 192'? F7 NVENTOR ATTORNEY Patented Jan. 19, 1932RAYMOND F. BACON,

F BRONXVILLE, NEW YORK RECOVERY OF SULPHUR FROM ROASTER GASESApplication filed May a,

This invention relates to the recovery of sulphur from roaster gases,and has for its object the provision of an improved method A ofrecovering sulphur in elemental form from roaster gases. Moreparticularly, the invention aims to provide an improved method ofrecovering elemental sulphur from roaster gases by preheating the airentering the roasting chamber and thus enriching the roaster gases insulphur dioxide.

Sulphur dioxide may he reduced to elemen tal sulphur by suitable hightemperature treatment with reducing agents, such as car- A bonaceousfuels, in the nature of coke or coal, liquids in the nature ofpetroleum, or gases in the nature of natural gas, producer gas, or watergas. When it is desired to carry out this reaction, making use ofroaster gases as the source of sulphur dioxide, the

,, lute nature of the roaster gases and the consequent low content ofsulphur dioxide tend to make the commercial practice impracticable. Thisis due directly from two causes; one is the immense volume of gases 2-3which must be heated to a high tem erature; the other is the difficultyof separating a comparatively small amount of solid sulphur from such alarge volume of gas.

I have discovered that the gases given oil from the roasting of suchmaterials, as ores in the nature of iron pyrites or other sulphideminerals or compounds, may be enriched in sulphur dioxide by preheatingthe air entering the furnace. This enrichment may be carried to such anextent t at the subsequent reduction of elemental sulphur and the re-.

covery of the reduced sulphur is entirely practicable. The preheating ofthe air I accomplish by making use of the excess heat L0 carri d by thegases leaving the reducing chamber.

I have found that it is not sufficient to furnish an intimate mixture ofthe air entering the roasting retort and the sulphur- 5 bearingcompounds within the retort. It is advantageous to construct theroasting retort in such a manner that, during the rotating of theretort, the sulphur-beating material is carried up the side of theretort and showered through the reacting air. I have found 192?. SerialNo. 189,842.

when roasting sulphur-bearing materials in this manner that in order tomaintain the combustion with sulphur at a suthcient rate to maintain thenecessary heat to properly support combustion, it is necessary to supplythe oxygen at a fairly rapid rate and the consequence is that there isnot time or contact enough to allow for the burning out of the oxygen inthe air.

in practicing the present invention, the air may be moved through theroasting chamber at a comparatively slow rate, provided that theentering air is heated to a sulficiently high temperature so that thereaction commences immediately upon its entrance into the retort, andpro vided also that the revolving retort is provided with longitudinalbailie plates which will carry the finely divided sul hur material upthe side of the retort and shower it down through the heated air.

The preheating of the air entering the roasting retort may be carriedout in any desired manner. The excess heat carried by the vapors leavingthe reducing chamber may be utilize-cl by suitable heat interchangeapparatus, or it may be found advantageous to make useof t .e exhaustgases given ofi' by the furnace which externally heats the roasting retort. Or a combination of these two methods may be used. it is essentialthat the air entering the roasting retort carry suflicient heat units topermit the oxidation reaction to commence immediately upon the entranceof the air into the roasting retort. In practicing the invention in thismanner, the gases leaving the upper or charging end of the retort aresubstantially saturated with sulphur dioxide, and carry a minimum ofunreacted oxygen.

Various forms of apparatus are available for the practice of theinvention. In the single figure of the accompanying drawing, I

have illustrated an apparatus satisfactory for V the purpose.

The apparatus illustrated in the'drawing comprises a rotating, inclined,cylindrical retort 5 of any appropriate material, adapted to Withstandcorrosive influences encountered in roasting sulphur-bearing compoundsto ob tain sulphur dioxide. The retort may be enclosed for the greaterpart of its length in an appropriate furnace structure 6. The lower heatthe incoming air. This apparatus, al-

or discharging end of the retort is operativethough not illustrated,would not depart ly connected to a heat interchange apparatus from thespirit of the invention. The type of 7 so that the air entering theroasting retort condenser may be changed to suit any oper is preheatedto a desired degree. The upper ating condition that may be met. The oxi-70 or charging end of the retort is operatively dizing retort may bealtered to better handle connected to the reduction furnace or chamanygiven type of sulphur-bearing material.

ber 10 by the pipe 9. In place of a tubular retort which showers Thereduction chamber is supplied with the pyrites through the gaseousstream, a rereducmg material in any appropriate mantort with mechanicalarms to keep the pyrites 75 ner. Coal or coke may be provided for thisstirred up in contact with the gaseous stream purpose from the hopper 11through the may be used.

valved pipe 12. lhe reduced gases are with- I claim:

drawn from the reducing chamber 10 l. The method of recovering sulphurfrom through the opening 13, which is operatively roaster gas whichcomprises oxidizing sul- 8 connected with the heat interchangeapparaphur compounds thereby forming sulphur ditus 'Z and with thecondenser 15 by the pipe oxide, reducing the said sulphur dioxide and1d. using the heat of reduction to aid the oxida- The condenser 15 ispro ided with cooling tion of the said sulphur compounds.

coils 1.6 and 17, and is divided into two por- 2. The method ofrecovering sulphur from tions by a battle wali 18. Suitable valvedsulroaster gas which comprises preheating air,

phur withdrawing passages 19 are provided oxidizing sulphur compoundswith the said in the condenser coinoartinent bottoms and a preheated airthereby producing a roaster gas exit passage 20 releases the spent gasesgas rich in sulphur dioxide, reducing the said 5 from the processes.sulphur dioxide of the roaster gas and utiliz- The operation of theapparatus will be uning the heat of reduction to preheat the allderstood from the foregoing description. and aid the oxidation of thesaid sulphur Sulplnir-bearing material in the nature of mpounds. pyritesis fed into the retort through the The method of recovering sulphur from30 hopper 21. Air to support combustion is adroaster gas which comprisespreheating air, mitted through the opening 22 and is heated oxidizingsulphur compounds with the said in its passage through the heatinterchanger preheated an thereby producing a roaster gas 7. A heatedair is forced i to th roa ti rich in sulphur dioxide, reducing the saidsult t. fl h th passage 23, Th spent phur dioxide of the roaster gas andutilizing cinder or ash is withdrawn from the lower the g s pr du d d rig h r du t n to 1 0 end of the retort 5 through the spout 2a. preheatthe air and aid the oxidation of the During the o eration of the retortexternal Said sulp r COITIPOUHClS- heat ma be ap lied to the retort bymeans of in t t y w o I affix y g a e. the furnace 6. The roaster gasesissuing from RAYMOND CO the upper or charging end of the retort passthrough the pipe 9 into the reduction furnace or chamber 10, where theyreact with the heated reducing material and are withdrawn from thechamber through the pasas; l3, and the pipe let passing through the heatinterchanger 7 In the heat interchan ger they give up part of their heatto the air entering the process The gases then pass to the condenser 15where the cooling coils 16 and 17 chill the vapors and condense thesulphur into elemental sulphur, which falls to the bottom of thecompartments and is withdrawn through the valved openings 19. The spentgases pass from the apparatus through the passage 20. 12

While certain forms of apparatus have been illustrated, it is understoodthat these may be varied or changed at will without in any way departingfrom the spirit of the into vention. The use of a liquid or gaseous re-15 ducing agent in place of the solid carbonaceous fuel will necessitatea different type 0t reduction chamber. It may be desirable to use thewaste gases from the heating fur- 5 nace in a heat interchangerapparatus to pre- 1

